Crystalline indium phosphide (InP) is a technologically important III-V compound semiconductor for photovoltaic (PV) devices. For single-band-gap solar cells, it offers an optimal band gap for both space and terrestrial applications. It also has many important and useful characteristics for multi-band-gap PV systems. The inherently high resistance of InP to radiation damage gives it a special advantage for space applications. The interest in developing InP solar cell technology was very high for several years after the discovery of its high radiation resistance during the middle 1980s. However, despite its optimal band gap (1.35 eV at 300° K), the best PV performance of InP solar cells has historically been significantly less than that demonstrated for GaAs solar cells, which has a similar band gap (1.42 eV at 300° K). For example, under the standard global spectrum at one-sun intensity and at 25° C., the highest efficiency achieved for InP solar cells is ˜22%, whereas for GaAs solar cells it is ˜26% (note: these are efficiencies for conventional cells not employing back-surface reflectors (BSRs) and thin absorber layers to increase efficiency).
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.